Filled Silicone Composition Viscosity Control
Solution Overview
Problem
Prior silica-filled silicone compositions rapidly gel or have high dynamic viscosity at ambient temperature, making them unsuitable for applications requiring high silica loading, lower viscosities, higher cure speeds, and ambient temperature curability.
Innovation Solution
A filled silicone composition comprising in situ-prepared treated silica, (siloxane-alkylene)-endblocked polydiorganosiloxane, a cure catalyst, and a crosslinker, which is produced through a method involving treating silica with a treating agent and converting an alkenyl-endblocked polydiorganosiloxane in the presence of a SiH containing siloxane and hydrosilation catalyst, allowing for lower dynamic viscosity to silica concentration ratios at ambient temperature without the need for additional fluidizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silica loading is increased in silicone compositions, then reinforcement and structural properties are improved, but dynamic viscosity increases rapidly making the composition unsuitable for processing
Solution Approach 1:
The patent introduces a silane-treated silica preparation process where silane acts as an intermediary substance that modifies the silica surface. The silane treatment creates a compatible interface between silica and silicone polymer, preventing aggregation and reducing viscosity increase while maintaining reinforcement properties.
Solution Approach 2:
The patent changes the surface chemistry parameters of silica through silane treatment, transforming it from untreated to treated silica with modified surface properties. This parameter change in silica surface chemistry allows high loading without excessive viscosity increase, resolving the contradiction between reinforcement and processability.
2Strength
If silica concentration is increased to achieve high reinforcement, then tensile strength is improved, but cure speed decreases due to rapid gelation
Solution Approach 1:
The patent performs preliminary silane treatment of silica before mixing with the silicone composition. This preliminary action modifies the silica surface in advance to prevent rapid gelation during curing, allowing high silica concentrations to maintain both high tensile strength and adequate cure speed.
3Ease of operation
If dynamic viscosity is reduced to improve flowability, then applicability is improved, but additional fluidizers are required increasing formulation complexity
Solution Approach 1:
The silane treatment acts as an intermediary that naturally reduces the interaction between silica particles and the silicone matrix, achieving flowability improvement without requiring separate fluidizer additives. This eliminates the need for additional formulation components.
Solution Approach 2:
The silane treatment serves multiple functions simultaneously: it reinforces the silica, prevents aggregation, controls viscosity, and enables flowability without requiring separate fluidizers. This multi-functionality reduces formulation complexity while achieving the desired flow characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves lower dynamic viscosity to silica concentration ratios, enabling improved flowability and cure speed, while maintaining high tensile strength and elongation, making it suitable for various adhesive, coating, and sealing applications.
Implementation Method 1
converting the AE Polymer in the LSR MB with a converting effective amount of a SiH containing siloxane (ingredient (b2)) and a catalytically effective amount of a hydrosilation catalyst (ingredient (b3))
Implementation Method 2
treating an untreated silica (ingredient (a1)) with a treating effective amount of a treating agent (ingredient (a2))
Implementation Method 3
a crosslinking effective amount of a crosslinker (D)... mixing the SCP MB with sufficient amounts of the cure catalyst (C) and crosslinker (D)
Data Source
Figure 1~2
AI summary
Filled silicone composition, in situ preparation and use thereof are provided. The composition comprises a mixture of (A) an in situ-prepared treated silica, (B) an in situ-prepared (siloxane-alkylene)-endblocked polydiorganosiloxane, (c) a cure catalyst and (D) a crosslinker. Moreover, the composition can be used as adhesive, coating and sealant.